Art of protecting metal surfaces



Patented F eb. 20, 1945 UN'ITED STATES'PATENT orrlcs Jacob MauriceCohen, Washington, D. C.

No Drawing. Application January 25, 1941. Serial No. 375,993

8 Claims. 106-14) This invention relates to the art of protectingsurfaces of metals such as iron, aluminum, magnesium, zinc, copper andalloys thereof such as steel, brass, and the aluminum-magnesium alloys,when exposed to fresh or sea water, to the atmosphere, and to likeactive influences.

It has heretofore been proposed for this purpose to employ variousmixtures of soaps, oils and greases, and pitches or asphalts; but suchmaterials have not been effective and available for providing asatisfactory continuous, thin, adherent and protective coating which canbe easily andsimply supplied and removed.

- A feature of the present invention, therefore, is the provision of acomposition which can be so employed, and which can be utilized inseveral forms or conditions according to the purposes to be attained.

In order to assure proper adhesion, compounds are selected which arecapable of afilxing themselves to metal surfaces, and may becharacterized as polar compounds with cation properties and chargeswhich are attracted by the metal so that the substances thus becomedeposited upon the exposed surface, and resist. removal by simplemechanical means. Such compounds are preferably provided in the form ofa solution or suspension in a volatile solvent which permits themolecules of the polar compound to be delivered to the metal surface toestablish a continuous and thin film thereon.

The composition comprises ingredients which ently preferred. Chemically.pure lanolin has surface and closely adherent thereto. Further. such afilm preferably must be capable of quick and easy removal by easilyavailable and employable means, such as a hydrocarbon lubricant which isto be active upon the cleared surface, or condensed-steam when thecomposition has been used to protect the steam-exposed surfaces ofpipes, etc.

The basic fatty substance is present as a major ingredient of the base.It has been found that lanolin or wool fat is highly satisfactory forthe purpose, and is the presently preferred material. It is desirablethat this lanoliii should be free of substances which may interfere withits capabilities of adherence to'the metal surface. Commercial lanolin,being apuritled wool fat. is presbeen found utilizable but lesseffective, and the relatively impure wool grease has a sufficient effectfor many purposes; and other animal fats such as lard, tallow, etc.may-be substituted when proper precaution is taken with respect to otheringredients including agents for preventing rancidity. These fattysubstances are characterized in containing the fatty esters.ofwater-insoluble aliphatic acids such as oleic, palmltic, stearic,lanopalmic, lanoceric. etc., and having at least I substantially 16carbon atoms in the carbon are effective conjointly to accomplish thedeposition of an adherent film and to maintain this film in place andresistant to the aforesaid in' fluences. It comprises a substantiallyneutral fatty material of unctuous or greasy consistency, a higheraliphatic acid, and a substance competent of offsetting any tendencytoward excessive effect of the acid and preferably also being effectiveas an inhibitor of change in the other materials and itself having polarproperties. Such a composition may have added thereto an extremely fine,preferably colloidal, metallic oxide, such as cuprous oxide, a lowerlead oxide, etc., as a preservative and stain for indicating that themetal surface has been properly covered. For the usual application of athin and adherent film, the basic composition is extended by a volatilesolvent so that it may be employed in a dilute condition; and such acomposition is effective for permitting the deposition of the polarcompounds during the course of evaporation of the solvent, with anassurance that the film will be continuous over the metal solvents,rather than a-uniform film. Butter is' excepted from the fattysubstances 'utilizable as chain. It has been found that compositionsineluding tallow aremore waxy than those with lanolin, and have a markedadherence so that it is difiicult to remove the film later: while thosewith lard tend to form rings with hydrocarbon being a substance in whichacid radicals have relatively few carbon atoms in the carbon chain, saidacids commonly being classified as watersoluble. r

The higher aliphatic acid is a substantially saturated material anditself a polar compound which contains a carboxyl group capable of at-'tachment to a metal surface, with an aliphatic chain which renders itcapable of blending with or effecting a Joint solution with thefatty'substance. Water-insoluble monocarboxyl acids are valuable, asbeing little subject to change? and preferably have a straight chainformation of, say, ten to twenty carbon atoms. Lower members tend towardwater solubility: while'higher members are too stiff in desirableproportions of composition. Oleic acid is the presently preferredmaterial, although other substances of this nature, such as stearieacid, palmitic acid. and the like may be employed as a full or partialsubstitute. n

In order to prevent an excessive action of the oleic acid, by whichdirect attack upon the metal might occur, a tertiary amine is employed,and appears to be effective without far-reaching direct esterificationof the oleic acid. Triphenylamine, triethanolamine, and other aryl,alkyl, and

alkaryl tertiary amines may be used; a, solution in thiocyanate isadvantageous. Quaternary amines having the properties of the specifiedtertiary amines are also effective.

A basic composition thus comprises lanolin or wool fat, about 75 partsby weight; finely divided cuprous oxide, about to 15 parts (preferablyabout 2 percent); oleic acid, about 5 percent: and a tertiary aromaticamine for neutralizing, about /2 to 5 parts (preferably about 1percent). This basic composition is then completed by extending in ahydrocarbon solvent in the proportions by volume of about 20 percent ofthe base to 80 percent of mineral spirits, naphtha, or other likevolatile or low boiling compound or mixture. In compounding thematerials, it is preferred to dissolve the lanolin, oleic acid andtertiary amine in individual quantities of the solvent, and then to mixthese mechanically while introducing the cuprous oxide. Finally, thebasic composition is completed by intro- :ducing the rest of thesolvent.

I This composition is capable of direct employment, particularly uponwarming of composition and article for securing an economically thincoating; but preferably is further modified to obtain certain valuablecharacteristics which adapt the material to specific purposes.

- Example I A composition, which may be used for the cleaning of metaland metal surfaces and for the .lubrication and continued protection ofsuch sur- Iaces by the deposit of a thin film of preservative Y andlubricating nature, is prepared by taking substantially 30 parts of theabove diluted basic composition, with 3 parts of a lubricating oil suchasSAE 30 toSAE 0, and 66% parts of a volatile chlorinated hydrocarbonsuch as carbon tetrachloride, trichlorethylene, or the types employed inrefrigerating machines. These ingredients are stirred until a uniformmixture results. l This composition is particularly useful in cleaningdust, grease, cosmoline, etc., from machine tools, printing machinery,boilers, engines, turbines, ypewriters, precision instruments,addmachines, etc. It is effective not only for removing the accumulationof hardened grease,

oil and dust, but leaves a thin coating of fiuid nature which provideslubrication. It is effective, for example, to prevent corrosion of metalafter contact of metal by sweating hands.

For-use on typewriters and like machines, one and. two thirds percent ofoil is preferred: for use inside steam or internal combustion enginesfive percent are desirable. One and a half percent is a desirableeconomic minimum to maintain.

' It may be applied by spraying under high pressure of 100 to 150 poundsper square inch, or even by spraying at low pressures with a hand spray:and can be employed directly by a brush, by --d1pp1n8. by. a rag, or byflushing, i. e., by filling the article therewith and then emptying.

'. The film is non-drying, and provides a sub stantial protectionagainst corrosion. If desired, it may be removed by common solvents suchas kerosene, gasoline, carbon tetrachloride, etc. The film is a fewten-thousandths of an inch thick and is transparent, so that thecondition of the surface may be observed. It is non-abrasive,non-drying, non-inflammable under ordinary conditions, and is harmlessin contact with the skin.

Example 11 A composition which is effective upon metal surfaces whichhave been wet with water, to displace this water and provide a.protective film, may be made by mixing substantially 95.6 parts of thediluted basic composition above with 4.4 parts of a wetting agent. Thiswetting agent should be soluble in the hydrocarbon solvents, and also inwater. Various commercial agents of this type may be employed, such asdioctylsodium-sulfosuccinate (commercially available as Aerosol OT).

This composition may be employed by spraying or by direct dipping,brushing, etc. After evaporation of the solvent, a thin adherent film isleft. When employed upon metal which has been wetted, as by immersion ofmachinery or instruments in salt wate, the surfaces may be directlytreated with this composition, without prior removal of all the waterand adherent moisture. It appears least active on metal in the presenceof distilled water, but its activity increases as the concentration ofelectrolyte in the water increases. It operates to penetrate anddisplace the water from the metal surfaces and forms its protectivecoating directly upon the metal. i

It can be removed by the presence of an excess of water, particularly ifhot, and hence it is useful in rust-proofing the waterside of boilertubes,

the steam or waterside of engines, pumps, etc., when ships aredecommissioned: in such cases, no problem of removal is involved, as thefilm immediately forms an emulsion in the presence of an excess of wateror the condensed steam, and is immediately ejected. Further, it blendswith normal lubricants, so that the engine, etc., of the decommissionedship can be immediately started after the 'same oiling as would beemployed upon cleaned surfaces. However, it can be cleaned away, if sodesired, by use of the standard solvents of lanolin.

I The film deposited by this composition is usually somewhat thickerthan the film deposited by the composition of Example I, but is lessthan a half-thousandth in thickness, non-drying.

transparent, non-abrasive, and harmless in contact with the hands.

Example III A composition for permanent protection of metal which may beexposed to severe weather conditions can be prepared by mixing 72.4parts of the diluted basic composition above, 21.4 parts of non-acidbituminous base material (preferably polar) which may contain about 4percentof a leaded compound, and 6.2 parts of a hard wax. The bituminousbase material may be selected from the asphaltic or tar distillateshaving a high boiling point and of non-acid character such as Aloxcommercial oxidired petroleum fractions, usually being a complex mixtureof organic esters, alcohols, lactones, and ketones of high molecularweights; being about 8200,sp.gr., 40-43 B., viscosity 48-58 seconds(Baybolt) at 210, inp. 104-107 F" flash 350-370 aacacse acid number0.0-5.0, iodine number 20.

R, (maximum): neutral or slightly-alkaline roofin asphalts areeffective. The hard-wax is preferably a hard petrolatum wax, such asPetrowax, but neutral waxes such as carnauba. montan, petrolatum, etc.,waxes, may be employed to give the desired body so that dirt particleswill not cut through easily.

This composition has a much darker color than those of the aboveexamples, and deposits a film less than a thousandth of an inch thick,with a sufficient transparency to permit inspection of the conditions onthe metal surfaces. It can be employed upon machinery of all kinds,gives excellent surfaces on machinery which is used or stored outdoors,and protects even against frequent handling or abrasion of machineryindoors I or outdoors. The film is heavier than those of thecompositions above, and normally this composition is not recommended foremployment on sensitive instruments, where' the thickness or weightcharacteristics may be of importance.

The composition may be employed by dipping, spraying or brushing, butshould be employed upon a clean metal surface from which all foreignmatter has been removed. For example, the compositions of the aboveexamples may be used to clean the surface and expel moisture, and thenthe present composition may be employed directly over the film depositedthereby.

The film is sumciently transparent, non-abra' sive, harmless in contactwith the skin, soluble in any of the aforesaid common solvents and inlubricating oils, and is capable of providing protection for at leasttwo years for metal surfaces exposed to outside conditions, providedthat the film is not removed by a solvent or by abrasion during thetime.

Example IV A composition similar to that of Example 111, but providing athinner film not so resistant to abrasion by wind or water, may beprepared by mixing 65 parts of the diluted basic composition above, and35 parts of petrolatum.

This composition deposits a film which is capable of preserving metal ofall kinds against corrosion during storage or use indoors, and may beemployed on machine tools, hand tools, fine instruments, engines,turbines, dies and fixtures, metal sheets, tinplate, etc. Thecomposition may be applied by dipping, spraying or brushing, and shouldbe applied over a clean metal surface: the surface may be cleaned by theuse of the compositions of Examples 1 and II above, and then the presentcomposition applied directly thereover. The film may be removed, ifdesired, by use of the common solvents or lubricating oil.

The deposited film is sufllciently transparent. non-abrasive, harmlesstothe skin, and may be easily removed when so desired. On metal surwithlubricant, water, etc., in contact with the mospherlc influences.

protected surfaces which thereby are cleared of the protecting compound,so that the clean metal is shortly provided for contact with any slidingparts, etc or the waterside of boiler tubes may be quickly cleared ofthe material for efflcient heat transfer.

With each composition, the coating is very thin, beingof the order ofless t an a thousandth of an inch, and is stable a inst any normal at-The films are extremely tenacious, and correspondingly resistant to the.penetration of any reagent which is not a solvent thereof.

,It is obvious that the invention is not limited to specific examples ofpractice as stated, but that compositions may be made and employed invarious ways, within the scope of the appended claims.

I claim:

1. A liquid composition for depositing a protective film upon metals,comprising a base and a faces which are stored indoors, the film has apro- Examples 111 and IV, it is preferred toemploy the compositions ofExamples 1 and II, for

" preliminary cleaning operations. With any of these compositions, themetal is the mechanism may be immediately returned to service byoperating it under normal conditions volatile solvent therefor; saidbase having as the major ingredient thereof parts by weight of asubstantially neutral semi-solid polar fatty compound of unctuousconsistency and of cation properties and having the acid portion of themolecules thereof essentially consisting of a water-insoluble aliphaticacid with at least sub-, stantially 16 carbon atoms in the carbon chain,and also including about 5 parts of a waterinsoluble higher aliphaticacid with 10 to 20 car-- bon atoms in the aliphatic chain whereby thesaid higher acid is compatible with the animal fat, and to 5 parts of atertiary amine present in an amount for preventing far-reaching directesterification of the said higher-acid.

2. A liquid composition for depositing a protective film upon metals,comprising a base and a volatile solvent therefor; said base having asthe major ingredient thereof 75 parts by weight of a substantiallyneutral semi-solid polar animal fat of cation properties and having theacid portions of the molecules thereof essentially consisting of awater-insoluble aliphatic acid with at least substantially 16 carbonatoms in the carbon chain,

,and also including about 6 parts of a water-insoluble higher aliphaticacid with 10 to 20 carbon atoms in the ,aliphatic chain whereby the saidQhigher acid is'compatible with the animal fat, and /2 to 5 parts of atertiary amine present in an amount for preventing direct attack by thesaid higher acid upon the metal and for preventing far-reaching directesteriflcation of the said higher acid.

3. A liquid composition for depositing a protective film upon metals.comprising a base and a volatile solvent therefor; said base having asthe major ingredient thereof .75 parts by weight of lanolin, and alsoincluding about 5 parts 'of a weter-insoluble higher aliphatic acid with10 M30 carbon atoms in the aliphatic chain whereby the acid iscompatible with the animal fat, and V to 5 parts of a tertiary aminepresent in an amount for preventing direct attack by the acid upon themetal and for preventing far-rechinlg direct'esterification of the acid.

protected: but

4. A liquid composition for depositing a protective film upon metals,comprising a base and a volatile solvent therefor; said base having asthe major ingredient thereof 75 parts by weight of lanolin, and alsoincluding about 5 parts of a water-insoluble higher aliphatic acid with10 to 20 carbon atoms in the aliphatic chain wherewater-insoluble higheraliphatic acid with 10 to I 20 carbon atoms in-the aliphatic chainwhereby the acid is compatible with the animal fat, and to parts of atertiary amine present in an amount for preventing direct attack by theacid upon the metal and for preventing far-reaching directesteriflcation of the acid, said solvent being present in a proportionof approximately 4:1 relative to the base. and also including petrolatumin a proportion of approximately onethird of the composition.

6. A liquid composition for depositing a protective'i'ilm upon metals,comprising a base and a volatile solvent therefor; said base having asthe major v ingredient thereof 75 parts by weight of lanolin, and alsoincluding about 5 parts of a water-insoluble higher aliphatic acid withto 20 carbon atoms in. the aliphatic chain whereby the acid iscompatible with the animal fat, and

/2 to 5 parts of a. tertiary amine present in an amount for preventingdirect attack by the acid upon the metal and for preventing far-reachingdirect esterification of the acid, and also including anon-acidbituminous base in the approximate proportion of /5 of the composition,and also containing a hard wax in the proportion of from 1 to 10 percentof the composition.

7. A liquid composition for depositing a protective film upon metals,comprising a base and a volatile solvent therefor; said base having asthe major ingredient thereof 75 parts by weight of lanolin, and alsoincluding about 6 parts of a water-insoluble higher aliphatic acid with10 to carbon atoms in the aliphatic chain whereby the acid is compatiblewith the animal fat, and 1 to 5 parts of a tertiary amine present in anam unt for preventing direct attack by the acid upon the metal and forpreventing far-reaching direct esteriiication of the acid, and 1 to 8percent of a wetting agent soluble in water and in said solvent. 8.;Aliquid composition for depositing a protective film upon metals,comprising a base and a volatile solvent therefor; said base having asthe major ingredient thereof 75 parts by weight of lanolin, and alsoincluding about 5 parts of a water insoluble higher aliphatic acid with10 to 20 carbon atoms in the aliphatic chain whereby the acid iscompatible with the animal fat, and to 5 parts of a tertiary aminepresent in an amount for preventing direct attack by the acid upon themetal and for preventing far-reaching direct esteriiicatlon of the acid,said solvent com prising light mineral spirits and a chlorinated lighthydrocarbon, and also containing a' few percent of a lubricating oil.

JACOB MAURICE COHEN.

